1. Field of the Invention
The present invention relates to a tenon formation method and more particularly, to a method of forming a tenon on one side of a metal plate member that has a relatively greater height to fit different design applications, more particularly the fabrication of a mobile memory stick.
2. Description of the Related Art
Forming a tenon on one side of a metal plate member for the connection of a swivel member is a pivot joint technique. During formation of this tenon, the other side of the metal plate member must be kept smooth without deformation. A conventional tenon formation method, as shown in FIG. 7, is the use of a punch to punch a metal plate member 90, thereby forming a tenon 901.
The punch 91 has an outer step 911, an inner step 912 and a recess 913 at the center of the inner step 912. When punching the metal plate member 90 with the punch 91, the inner step 912 will be driven into the wall of the corresponding side of the metal plate member 90, causing a part of the metal plate member 90 to be deformed into the desired tenon 901 by the recess 913.
This method can form an upwardly protruding tenon 901 at one side of the metal plate member 90, however the finished tenon 901 has a limited height. After installation, the connected member may fall from the tenon 901 accidentally.
FIGS. 8˜10 show an application example of the aforesaid tenon 901 in a swivel type mobile memory stick. As illustrated, the swivel type mobile memory stick 92 comprises an inverted U-shaped metal plate member 921 and a casing 922. The casing 922 accommodates a PC board 923 that has a USB connector 924 located on one end and extended out of the casing 922. The inverted U-shaped metal plate member 921 has two tenones 901 protruded from the inner wall thereof at two opposite sides and respectively pivotally connected to a respective pivot holder 925 on the casing 922 such that the inverted U-shaped metal plate member 921 is turnable relative to the casing 922 between a close position and an open position to close or open the USB connector 924, as shown in FIGS. 9 and 10.
According to this design, the tenones 901 have a limited height. Thus, the connection area between the tenones 901 of the inverted U-shaped metal plate member 921 and the pivot holders 925 of the casing 922 is limited, as shown in FIGS. 8-10, and therefore, the tenones 901 of the inverted U-shaped metal plate member 921 tend to be forced away from the pivot holders 925 of the casing 922 accidentally. An improvement in this regard is necessary.